Wastewater source control system

ABSTRACT

A wastewater source control system for use with a sewer service line conducting a flow of wastewater from a building to a sewer main. A flow control device is installed in the sewer service line with an upstream detention tank to detain building wastewater upstream from its point of discharge into a sewer main during certain heavy stormwater runoff periods.

This application is a continuation-in-part of application Ser. No.10/678,009, filed on Oct. 2, 2003, which is hereby expresslyincorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to sewage collection systems including bothsanitary sewers and combined sewers.

BACKGROUND OF THE INVENTION

For purposes of clarification and understanding of this document, thefollowing definitions are set forth. The term “wastewater” designatescontaminated domestic wastewater such as “sanitary sewage” as well aswater that carries away other waste matters from households, mercantile,commercial, and industrial establishments. “Stormwater” refers torainfall runoff waters collected in sewers. “Extraneous inflows” referto waters that enter a sewer collection system by infiltration fromground waters and by inflow from surface water sources especially duringstormwater runoff periods. “Combined sewer systems” carry “combinedsewage” that is a mixture of wastewater and stormwater plus a certainamount of extraneous inflows. In separate wastewater sewer systems,“wastewater mixtures” are the result of wastewater mixing withextraneous inflows.

Combined sewer systems are designed to transport combined sewage in theform of wastewater plus a much larger allowance in flow capacity forstormwater and a minor allowance for extraneous inflow. Combined sewageis commonly collected in municipal combined sewer systems; and duringlow flow periods, combined sewage is mainly comprised of wastewaterwhich is directed via an interceptor pipeline to a wastewater treatmentplant. However, when heavy stormwater flows occur, combined sewer flowsoften exceed the flow capacity of the interceptor; and the overflow isdiverted into a receiving watercourse such as a natural stream or river.These overflows are referred to as combined sewer overflow (“CSO”).However, in high rainfall climates over an annual period, CSOs may be afrequent occurrence resulting in receiving water pollution.

Separate wastewater sewer systems are designed to transport wastewaterplus a limited allowance for extraneous inflow. They do not have directstormwater connections to surface water inlets as do combined sewers.Although separate wastewater sewer systems are intended to carry mainlydomestic wastewater, during high rainfall runoff periods, they also maybecome overloaded due to extraneous inflows and therefore, carry awastewater mixture, which is usually a more concentrated form ofcombined sewage. Overflows from separate wastewater or sanitary sewersystems are generally referred to as a “Sanitary Sewer Overflow”(“SSO”). SSOs generally contain a larger wastewater or sanitary sewagecomponent and are of higher pollution concentrations than CSOs fromcombined sewers.

There is a continuing effort to reduce water pollution in watercourses,streams, rivers, lakes, oceans, and other receiving bodies of water fromCSO, which is emphasized in the U.S. Environmental Protection Agency(EPA) guidance documents including “Combined Sewer Overflow (CSO)Control Policy (66 FR 42226)” and “Coordinating CSO Long-term Planningwith Water Quality Standards Reviews (EPA-833-R-01-002; July 2001)”.

Therefore, there is a need during heavy stormwater runoff periods toprevent, or to some substantial degree avoid, the creation of combinedor mixed sewage, thereby reducing CSO and SSO pollution concentrations.

SUMMARY OF THE INVENTION

The present invention is a sewage control system that prevents orreduces the pollution content of combined sewage or wastewater mixtureswhich often overflow from sewer systems into watercourses, streams,rivers, lakes, oceans, and other receiving bodies of water as a resultof heavy rainfall runoff and infiltration.

According to the principles of the present invention and in accordancewith the described embodiments, the invention provides a wastewatersource control system for use with a sewer service line conducting aflow of wastewater from a building to a sewer main. A flow controldevice is installed in the sewer service line; and an actuator isconnected to the flow control device. The actuator, in response to anoutput signal from a hydrologic sensor, causes the flow control deviceto block the flow of wastewater to the sewer main and detain the flow ofwastewater in the sewer service line.

In one aspect of the invention, the hydrologic sensor is either a flowsensor monitoring a flow in the sewer main or a rainfall sensor. Inanother embodiment of the invention, in response to the output signal,the wastewater in the sewer service line is detained in a detentiontank. In a further embodiment of the invention, the wastewater in thedetention tank is pumped therefrom with a sump pump.

In a further embodiment of the invention, the flow control device is anautomatic backflow prevention valve that is used with a detention tanklocated upstream of the valve. With this embodiment, the hydrologicsensor and associated actuator are not required.

By detaining building wastewater upstream from its point of dischargeinto a sewer main during certain heavy stormwater runoff periods, thecreation of combined or mixed sewage is prevented or to some substantialdegree avoided, thereby reducing CSO and SSO pollution concentrations.

In a still further embodiment, the invention provides a system ofseveral wastewater source control systems in which each system has aplurality of flow control devices and a plurality of actuators. Eachflow control device is installed in association with one of the sewerservice lines, and each actuator is in electrical communication with ahydrologic sensor and connected to a respective one of the flow controldevices. In response to the hydrologic sensor providing an outputsignal, each actuator causes a respective one of the flow controldevices to block the flow of wastewater from a respective one of thesewer service lines into the sewer main and detain the flow ofwastewater in the respective one of the sewer service lines. In oneaspect of this embodiment, the operation of the wastewater sourcecontrol system is controlled by a computer.

These and other objects and advantages of the present invention willbecome more readily apparent during the following detailed descriptiontaken in conjunction with the drawings herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a wastewater source control systemin accordance with the principles of the present invention.

FIG. 2 is a schematic illustration of an alternative embodiment of thewastewater source control system of FIG. 1 utilizing a differenthydrologic sensing device.

FIG. 3 is a schematic illustration of further embodiments of thewastewater source control system of FIG. 1.

FIG. 4 is a schematic illustration of another embodiment of thewastewater source control system of FIG. 1, which uses a detention tanknear a downstream end of a sewer service line.

FIG. 5 is a schematic illustration of an alternative embodiment of thewastewater source control system of FIG. 4, which uses a detention tankin a building near an upstream end of a sewer service line.

FIG. 6 is a schematic illustration of another embodiment of thewastewater source control system of FIG. 4, which uses a detention tankand a sump pump inside a building.

FIG. 7A is a schematic illustration of normal flow of a furtherembodiment of a wastewater source control system that does not require ahydrologic sensor and associated components in accordance with theprinciples of the present invention.

FIG. 7B is a schematic illustration of the wastewater source controlsystem of FIG. 7A under high flow conditions.

FIG. 8A is a schematic illustration of normal flow of a still furtherembodiment of a wastewater source control system that does not require ahydrologic sensor and associated components in accordance with theprinciples of the present invention.

FIG. 8B is a schematic illustration of the wastewater source controlsystem of FIG. 8A under high flow conditions.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, in one embodiment, drains 15 as well as plumbingfixtures, for example, one or more commodes 16, tubs 17, sinks 18, etc.,are connected to one or more soil stacks 19 in a building 20 anddischarge wastewater through a building drain piping 22. The building 20can be used for residential, commercial, or industrial purposes. Thebuilding drain piping 22 is connected to an intake or upstream end 23 ofa building sewer service line 24, which is located below grade 25 and isoften 6 inches (15 centimeters) or more in internal diameter for asingle family dwelling. A discharge or downstream end 27 of the sewerservice line 24 is connected to a sewer main 34. For purposes of thisdocument, “downstream” refers to a location nearer to, or a directionextending toward, the sewer main 34, and “upstream” refers to a locationnearer to, or a direction extending toward, the building 20.

A wastewater source control system 21 has a flow control device 26 thatis connected in the sewer service line for controlling a flow ofwastewater in the sewer service line 24. Most often the flow controldevice 26 is located near the downstream end 27 of the sewer serviceline 24. The automated flow control device 26 is located in a servicebox 28 to provide access for maintenance and may be a valve or anydevice that provides the intended service. The flow control device 26 isoperated by an actuator 40 and may be powered by electricity from abattery or other source, air or other fluid pressure, water or otherhydraulic pressure, or another source of energy.

A hydrologic sensing device is used to detect a high flow in a sewermain 34 or an event, for example, rainfall, that would create a highflow in the sewer main 34. In FIG. 1, the hydrologic sensing device maybe any device that indicates flow level, flow quantity or depth of flowin a receiving sewer main or a manhole, for example, a flow level sensor30, that is located in a manhole 32 and detects a level of flow througha sewer main 34. The sensor 30 provides flow output signals to a signaltransmitter 36, which transmits the flow output signals to a signalreceiver 38. The transmitter 36 electrically communicates with thereceiver 38 using wired or wireless technology. The receiver 38 providesthe flow output signals to the actuator 40, which operates the flowcontrol device 26 accordingly. The sensor 30, transmitter 36 andreceiver 38 are powered by electricity from a battery or other source.

In use, during normal periods, the flow control device is open; andwastewater from the building 20 flows through the sewer service line 24,past the flow control device 26 and into the sewer main 34. Without theinvention, when the flow through the sewer main 34 includes wastewaterfrom the building 20 plus a heavy stormwater flow, a CSO is oftenproduced in a receiving watercourse. However, with the invention, theflow level sensor 30 detects a greater than normal flow level 42 andprovides a high flow signal, which is transmitted to the actuator 40 viathe transmitter 36 and receiver 38. The high flow signal causes theactuator 40 to close the flow control device 26, thereby detaining orstoring wastewater from the building 20 in the sewer service line 24.

Wastewater detention volume is approximately 1.5 gallons per ft. or 73gallons (276 liters) per 50 ft. (15.2 meters) of 6-inch (15-centimeters)diameter building service line. Although building sewer service linelengths and domestic wastewater discharge volumes vary greatly, it isestimated that these volumes will bridge a high percentage of abovenormal sewer main flows and thus, substantially minimize or prevent CSOsand SSOs.

As the stormwater flow event lessens, the flow level sensor 30 detects alesser flow level 44 in the sewer main 34 and provides a lesser flowsignal to the actuator 40 via the transmitter 36 and receiver 38. Thelesser flow signal causes the actuator 40 to open the flow controldevice 26, thereby restoring a flow of wastewater from the building 20,through the sewer service line 24 and into the sewer main 34.

It should be noted that the lesser flow 44 can be equal to or greaterthan a normal flow 46 through the sewer main 34. Further, if, while theflow control device 26 is closed, should the sewer service line 24become full as detected by the flow level sensor 30, the actuator 40causes the flow control device 26 to open, so that wastewater does notbackup into the plumbing piping of the building 20. The sensor 30 can beany device that is effective to detect that wastewater has filled thesewer service line 24 upstream of the flow control device 26, forexample, a float switch located in the sewer service line upstream ofthe flow control device 26. Alternatively, instead of using the sensor30, the flow control actuator can be designed to open in response towastewater substantially filling the sewer service line 24 upstream ofthe flow control device 26.

In a second embodiment of the invention illustrated in FIG. 2, thewastewater source control system 21 uses a rainfall sensor 48 as ahydrologic sensing device in place of the flow level sensor 30 ofFIG. 1. The rainfall sensor 48 may be any sensor indicating rainfallintensity or rainfall depth or accumulation. Studies have been done thatcorrelate an amount of rain to CSO and SSO events. Signals representingan amount of rainfall detected by the sensor 48 are provided to theactuator 40 via the transmitter 36 and receiver 38. Upon detecting anamount of rainfall that would provoke a CSO or an SSO, the actuator 40operates to close the flow control device 26. The period of time thatthe actuator 40 maintains the flow control device 26 closed isprogrammed into the actuator 40, and that period of time can be adjustedas the amount of rainfall detected by the rainfall sensor 48 increases.Further, actuator 40 can be set to allow for a lag time corresponding torising and falling flow in the main sewer 34 so as to avoid a CSO and/oran SSO.

The wastewater source control system 21 described with respect to asingle building of FIG. 1 can also be applied to a plurality ofbuildings. Referring to FIG. 3, a transmitter 36 is electricallyconnected to either a sewer main flow sensor 30 or a rainfall sensor 48and is also in electrical communications over a wired or wirelesscommunications link 50 with a plurality of receivers 38 a-38 n. Thus thehigh flow level signal is provided to a plurality of actuators 40 a-40 nthat are connected to and operate a respective plurality of flow controldevices 26 a-26 n, which are connected in a respective plurality ofsewer service lines 24 a-24 n conducting wastewater from a respectiveplurality of buildings 20 a-20 n. Thus, wastewater from a number ofbuildings 20 a-20 n that are in a common neighborhood or geographic areacan be temporarily detained or stored in respective sewer service lines24 a-24 n during an event, for example, a thunderstorm, that wouldnormally lead to a CSO or an SSO.

In a further embodiment, control of the wastewater retention can becentralized. A wastewater management facility 52 has a receiver 54connected to the communications link 50, which receives the signals fromthe transmitter 36. In this embodiment, the receivers 38 a-38 n are notreceptive to signals from the transmitter 36. Further, there are anumber of other wastewater source control systems 60, 62 that aresimilar to the wastewater source control system 58. The wastewatermanagement facility 52 receives signals from a plurality of hydrologicsensing devices 30, 48 that are located in the various wastewater sourcecontrol systems 58, 60, 62. By monitoring signals from the varioushydrologic sensing devices 30, 48, personnel in the wastewatermanagement facility 52 provide further signals via a transmitter 56 tothe receivers 38 a-38 n for operating the flow control devices 26 a-26 nin the various wastewater source control systems 58-62. Alternatively, acomputer system 53 within the wastewater management facility 52 canprovide signals controlling the operation of the flow control devices 26a-26 n in the wastewater source control systems 58-62 in response tosignals from the hydrologic sensing devices 38, 48.

Referring to FIG. 4, in situations where the sewer service line 24 isrelatively short or where more detention storage is needed, thewastewater source control system 21 provides a detention tank 64 that isinstalled in the sewer service line 24 to increase storage capacity. Thedetention tank 64 can be formed by using a tank component or enlarging asection of the sewer service line 24. Where more than one source isserved, the detention tank 64 should be enlarged and designed as needed.This may be applied for example in the case where the building 20 is amulti-family facility. The operation of the wastewater source controlsystem 21 of FIG. 4 is substantially similar to that previouslydescribed with respect to FIGS. 1-3. Under normal conditions, wastewaterflows freely through the sewer service line 24 and the detention tank64, past the flow control device 26 and into the sewer main 34. Underhigh flow conditions detected by the hydrologic device, the flow controldevice 26 is closed; and wastewater is detained in the detention tank64. Upon detecting lower flow conditions, the flow control device 26 isopened and normal wastewater flow is resumed. As before, the hydrologicsensing device may be implemented using a flow sensor 30 or a rainfallsensor 48.

Referring to FIG. 5, the detention tank 64 of the wastewater sourcecontrol system 21 may be provided in a basement or lower levelcontainment box in the building 20 if the sewer service line 24 is shortor for other reasons. During normal flow 46 in the sewer main 34, thebuilding wastewater discharges from its plumbing fixtures and flowsthrough the building drain piping 22, into the detention tank 64,through the tank outlet 76, through a cleanout 78 and out the sewerservice line 24 to the sewer main 34. As previously described, inoperation, the receiver 38 detects a high flow signal from thetransmitter 36 representing a higher flow 42 in the sewer main 34detected by the flow sensor 30. That high flow signal causes the flowcontrol device 26 to close and detain wastewater in the detention tank64. Typically, a round cross-sectional shape of light weight,non-corrosive materials will be most efficient for passage of flows. Thedetention tank 64 is provided with an air vent pipe connection 72 and anoverflow outlet 74 to bypass flow to the sewer service line 24 when thetank becomes full. A tank outlet pipe 76 is connected to a running trapand clean-out fitting 78 and then to the sewer service line 24 thatconnects to the sewer main 34. In an alternative embodiment, thedetention tank 64 may also be located outside the building 20 in anappropriate structure and may have a connection to one or morewastewater sources.

Referring to FIG. 6, in those applications where gravity flow isinadequate, that is, the building drain pipe 22 is lower than theupstream end of the sewer service line 24, the waste water controlsystem 21 includes a sewage pump 66. In this embodiment, the detentiontank 64 and sewage pump 66 are installed in an interior, lower portion,of the building 20. In operation, the combination of the detention tank64 and sewage pump 66 function as a flow control device to regulate theflow of wastewater from the building 20 during normal and excessive flowconditions in the sewer main 34. Under normal flow conditions in thesewer main 34, wastewater flows into the detention tank 64. A firstliquid level sensor 70, for example, a float connected to a movablecontact of a limit switch, detects a first, lower level of liquid in thedetention tank 64 and provides a signal to the sewage pump 66. Thesewage pump 66 operates in a known manner to pump wastewater out of thedetention tank 64, up through a discharge pipe 68, through a cleanout 78and into the sewer service line 24. Therefore, during normal sewer mainflow conditions, there is a substantial wastewater reserve capacity inthe detention tank 64. An air ventilation pipe 82 is provided from thedetention tank 64 for ventilation of any gases.

If an event occurs that leads to a high flow in the sewer main 34, thereceiver 38 detects a high flow signal from the transmitter 36representing a higher flow 42 detected by a hydrologic sensing device,for example, the flow sensor 30 or rainfall sensor 48. That high flowsignal from the receiver 38, via a relay or other means, interrupts theconnection of output signal from sensor 70 to the sewage pump 66.Therefore, the sensor 70 does not operate the sewage pump 66, andwastewater is able to accumulate in the detention tank 64 to levelsabove the sensor 70. Building wastewater is detained in the tank 64until the flow in the sewer main 34 again subsides to a lower level 44.A low flow signal is then provided by the flow level sensor 30, which istransmitted to the receiver 38 via the transmitter 36. The receiver 38provides the low flow signal to the sewage pump 66, thereby causing theoutput signal from the sensor 70 to be reconnected to the sewage pump66. The sewage pump 66 then operates to pump wastewater from thedetention tank 64 until it is below a level detectable by the sensor 70,and thereafter, the sewage pump 66 operates under low flow conditions asfirst described. A liquid level sensor 71 may be used to detect when thedetention tank 64 is full and provide an output signal to operate thesewage pump 66, thereby providing overflow relief.

While the embodiment of FIG. 6, demonstrates the use of the invention inthose applications where the building drain piping 22 is below the sewerservice line 24, the invention illustrated and described therein can beused where the building drain piping 22 is above the sewer service line24. In those applications, the tank 64 is used as a wastewater storagetank during periods of high flow in the sewer main 34.

In still further embodiments of the wastewater source control system,the complexities and costs of the hydrologic sensor and associatedtransmitter, receiver and actuator can be eliminated. In the embodimentof FIG. 7A, the wastewater source control system 21 uses a flow controldevice 26 that is an automatic backflow prevention valve. Such in-lineautomatic backwater valves for sewer service lines are commerciallyavailable, for example from the Jay R. Smith Manufacturing Co. ofMontgomery, Ala.

During normal flow periods, the flow control device 26 is open; andwastewater from the building 20 flows through the sewer service line 24,past the flow control device 26 and into the sewer main 34. Without theflow control device 26, when the flow through the sewer main 34 includeswastewater from the building 20 plus a heavy stormwater flow, a CSO isoften produced in a receiving watercourse. As shown in FIG. 7B, a heavystormwater flow may result in a surcharge condition, which is defined bya hydraulic gradient above the crown of the sewer. In such event,stormwater flow begins to backflow through the downstream end 27 of thesewer service line 24. Without the flow control device 26, during asurcharge condition, stormwater can backflow through the sewer serviceline 24 and through the drain 15 in the building 20. However, the flowcontrol device 26 in the form of an automatic backflow prevention valve26 responds to the presence of the backflow in the sewer service lineand automatically closes. The closed flow control device 26 prevents anyfurther backflow of stormwater through the sewer service line 24, andthe backflow of stormwater through the drain 15 in the building 20 isprevented.

As will be appreciated, the closed flow control device 26 also preventswastewater from the building 20 from flowing into the lower end 27 ofthe sewer service line 24 and into the sewer main 34. Further, while theflow control device 26 is closed, building wastewater can also backup inthe upstream portion 23 of the sewer service line 24 and backflowthrough the drain 15 in the building 20. Anticipating that event, manyautomatic backflow prevention valves are sold with warning systems thatalert occupants of the building 20 of a flow control device closure,during which time the building occupants should cease using plumbingfixtures. When the storm event is over and normal flow returns to thesewer main 34, as the stormwater recedes from the downstream portion 27of the sewer service line 24, the flow control device 26 automaticallyopens.

Prohibiting the use of plumbing appliances during the time that the flowcontrol device 26 is closed is a substantial inconvenience to theoccupants of the building 20. Further, it is highly probable that someoccupants will ignore, or not be aware of, the valve closing warning. Toeliminate that inconvenience, the present invention utilizes a detentiontank 64 that may be implemented using any device to provide the desiredwastewater storage, for example, an oversized piece of sewer serviceline, etc. Thus, while the flow control device 26 is closed, buildingwastewater is detained in the detention tank 64. After the surchargecondition has passed, the flow control device 26 responds to stormwaterflowing out of the lower end 27 of the sewer service line 24 andautomatically opens; and building wastewater again flows freely throughthe sewer service line 24 and into the sewer main 34. The detention tank64 then drains, and a normal flow condition as illustrated in FIG. 7A isrestored.

In an alternative embodiment of the wastewater source control system 21shown in FIG. 8A, the flow control device 26 is again an automaticbackflow prevention valve as previously described. However, in theembodiment of FIG. 8A, the flow control device 26 and the detention tank64 are located in a basement or lower level containment box in thebuilding 20. During normal flow 46 in the sewer main 34, the buildingwastewater discharges from its plumbing fixtures and flows through thebuilding drain piping 22, into the detention tank 64, through the tankoutlet 76, through a cleanout 78 and out the sewer service line 24 tothe sewer main 34. As previously described, as shown in FIG. 8B, a heavystormwater flow may result in a surcharge condition; and in such event,stormwater backflows through the sewer service line 24. The flow controldevice 26 responds to the presence of the backflow in the sewer serviceline and automatically closes. The closed flow control device 26prevents backflow of stormwater through the drain piping 22, the drain15 and into the building 20. While the flow control device 26 is closed,building wastewater is detained in the detention tank 64. After thesurcharge condition has passed, the flow control device 26 responds tostormwater flowing out of the sewer service line 24 and automaticallyopens; and building wastewater again flows freely through the sewerservice line 24 and into the sewer main 34. The detention tank 64 thendrains, and a normal flow condition as illustrated in FIG. 8A isrestored. As shown in FIG. 8B, a liquid level sensor 84 may be used todetect when the detention tank is full or close to full. In that event,the liquid level sensor provides an output signal to a warning device 86that provides an audible, visual or other sensory perceptible warningindicating that the detention tank is full. The occupants of thebuilding are thus warned not to continue to use the plumbing devices inthe building.

In the embodiments of FIGS. 4-8, the detention tank 64 and sewage pump66, if used, are sized according to hydrologic conditions needed todetain the discharge of building wastewater during higher than normalstormwater flows 42 in the sewer main 34. The volume of the detentiontank 64 is based on the storage of building wastewater discharges neededto bridge typical wet weather flow periods in the sewer main 34. Thisrequires a hydrologic analysis based on statistical rainfall dataperiods of the region in combination with typical wastewater dischargefrom domestic dwellings or building sources. For example, a 10 feet(3.05 meters) length of 12 inch (30.5 centimeters) diameter sewageservice line has a detention volume of approximately 58 gallons (220liters). Depending on the hydrologic region, this volume is in a rangesufficient to detain single family domestic sewage during most typicalperiods of a CSO. The detention tank 64 may be of any shape, dimensions,or volume which provide for efficient fluid flow and the intendedservice, however a round pipe or tank of lightweight flexible material,such as a high strength plastic, may be cost effective. In analternative embodiment, the detention tank 64 may also be locatedoutside the building 20 in an appropriate structure and may have aconnection to one or more wastewater sources. Further, as will beappreciated, the embodiments of FIGS. 4-8 may also be implemented inlarger system schemes as illustrated and described with respect to FIG.3.

All of the embodiments of the wastewater source control systems of FIGS.1-8 will work with any sewer main of any size constructed onhydraulically mild, open channel, flow bottom slopes, that is,sub-critical or tranquil flow, or on hydraulically steep, open channel,flow bottom slopes, that is, super-critical or rapid flow. However, thewastewater source control systems are expected to be more sensitive formild slope applications with prevailing sub-critical or tranquil flow.Further, the wastewater source control systems of FIGS. 1-6 will workfor typical domestic wastewater discharges, however, for certainnon-domestic building discharges, such as commercial or industrialwastes containing high concentrations of solids, a maceration device ora grinder pump is recommended for maintaining fluid flow. It should benoted that in all of the embodiments shown and described with respect toFIGS. 1-8, the flow control device 26 not only detains upstreamwastewater from the building 20; but the flow control device 26 alsoprevents wastewater from backing up from the sewer main 34 into thebuilding 20.

By using the various embodiments of the invention shown and describedwith respect to FIGS. 1-8, building wastewater is detained upstream fromits point of discharge into sewer mains during heavy stormwater runoffperiods. Thus, one advantage of the invention is that the creation ofcombined or mixed sewage is, in some applications, to some substantialdegree avoided and, in other applications, prevented. Another advantageof the invention is the reduction of pollution content of combinedsewage or wastewater mixtures that overflow from sewer systems intowatercourses, streams, rivers, lakes, oceans, and other receiving bodiesof water as a result of heavy rainfall runoff and infiltration. Afurther advantage of the invention is that it prevents wastewater frombacking up from the sewer main 34 into the building 20.

While the present invention has been illustrated by a description of anembodiment, and while such embodiment has been described in considerabledetail, there is no intention to restrict, or in any way limit, thescope of the appended claims to such detail. Additional advantages andmodifications will readily appear to those skilled in the art. Forexample, the described embodiment relates to a combined sewer system inwhich wastewater from the building 20 and stormwater are combined in thesewer main 34. As will be appreciated, in a separate wastewater systemin which there is one sewer main for wastewater and a second, separatesewer main for stormwater, overflows can still occur in the wastewatersewer main. In those applications, the various embodiments of theinvention described with respect to FIGS. 1-8 can be applied to theseparate wastewater system in the same manner as described herein inorder to eliminate or substantially reduce the occurrence of overflowsin the wastewater sewer main.

In the embodiments described herein, the flow control devices 26 areoperated by respective actuators 40; however as will be appreciated, inalternative embodiments, the flow control devices 26 can be operatedmanually to provide the desired detention of wastewater prior to itentering a sewer main. Such manual operation can be initiated by one ormore signals generated by a flow sensor or a rainfall sensor or, inresponse to instructions provided from a central wastewater managementfacility by broadcast or otherwise.

In the embodiment of FIGS. 5, 6 and 8 the detention tank 64 and sewagepump 66, if used, are located inside the building 20; however, as willbe appreciated, in an alternative embodiment, the detention tank 64 andsewage pump 66, if used, can be installed in a service box 28 locatedoutside the building 20.

In the embodiments shown in FIGS. 4 and 7, the detention tank 64 isshown at the downstream end of the upper portion 23 of the sewer serviceline 24. As will be appreciated in alternative embodiments, thedetention tank 64 may be located at the upstream end of the upperportion 23 of the sewer service line 24. Further, the detention tank 64can be located either inside or outside a perimeter of the building 20.In the embodiments of FIGS. 7 and 8, the flow control device 26 can alsobe implemented with a pinch valve, for example, a Type A, model 4700pinch valve commercially available from Red Valve Company of Carnegie,Pa.

Therefore, the invention in its broadest aspects is not limited to thespecific details shown and described. Consequently, departures may bemade from the details described herein without departing from the spiritand scope of the claims which follow.

1. A wastewater source control system for use with a sewer service line conducting a flow of wastewater from a sewage line of a building to a sewer main, the wastewater source control system comprising: a flow control device adapted to be installed in the sewer service line, the flow control device automatically closing in response to a backflow of wastewater and/or stormwater from the sewer main, through the sewer service line and toward the building, and the flow control device automatically opening in response to a normal flow of wastewater from the building, through the sewer service line and into the sewer main; a detention tank disposed in the sewer service line upstream of the flow control device, the detention tank detaining wastewater in response to the flow control device being closed and the wastewater draining from the detention tank upon the flow control device subsequently opening.
 2. The wastewater source control system of claim 1 wherein the flow control device is disposed near a downstream end of the sewer service line.
 3. The wastewater source control system of claim 2 wherein the detention tank is disposed near a downstream end of the sewer service line.
 4. The wastewater source control system of claim 2 wherein the detention tank is disposed near an upstream end of the sewer service line.
 5. The wastewater source control system of claim 1 further comprising a service box and the flow control device is disposed in the service box.
 6. The wastewater source control system of claim 1 wherein the detention tank and flow control device are disposed near an upstream end of the sewer service line.
 7. The wastewater source control system of claim 6 wherein the detention tank and flow control device are located inside a perimeter of the building.
 8. A method of reducing wastewater in a sewer main receiving the wastewater from a sewer service line connected to a sewage line in a building, the method comprising: providing a flow control device connected in the sewer service line and a detention tank connected in the sewer service line upstream of the flow control device; automatically closing the flow control device in response to a backflow of stormwater from the sewer main, through the sewer service line and up to the flow control device; and detaining the wastewater from the building in the detention tank while the flow control device is closed.
 9. The method of claim 8 further comprising: automatically opening the flow control device in response to a flow of stormwater away from the flow control device; and automatically draining the wastewater detained in the detention tank in response to the flow control device being open. 